US7522347B2ActiveUtilityPatentIndex 63
Zoom optical system and electronic imaging apparatus using the same
Est. expiryNov 22, 2026(~0.4 yrs left)· nominal 20-yr term from priority
G02B 15/1445
63
PatentIndex Score
2
Cited by
8
References
20
Claims
Abstract
A zoom optical system comprises a lens group 1 having one negative lens component and a lens group 2 wherein a distance on the optical axis between the lens group 1 and the lens group 2 is changed for magnification purpose. The negative lens component consists of a cemented lens of positive lens and a negative lens, and when a straight line expressed by θgFp=αp×νdp+βp (αp=−0.00163) is set up in a rectangular coordinate system in which a horizontal axis is expressed by νdp and an vertical axis is expressed by θgFp, νdp and θgFp of the positive lens are included in domains specified by the following conditions. 0.6400<βp<0.9000 3<νdp<27 here, θ gFp is a ratio of a partial dispersion (ng−nF)/(nF−nC) of the positive lens L AP ; νdp is Abbe number (nd−1)/(nF−nC) of the positive lens L AP ; nd, nC, nF, and ng are refractive indices of d,C,F and g line, respectively.
Claims
exact text as granted — not AI-modified1. A zoom optical system comprising;
a lens group A having one negative lens component at the most object side, and a lens group B arranged adjacent to the lens group A, where a distance on the optical axis between the lens group A and the lens group B is changed for magnification purpose,
wherein
the negative lens component is a cemented lens consisting of a positive lens L AP and a negative lens L AN , and
when in a rectangular coordinate system in which a horizontal axis is expressed by νdp and an vertical axis is expressed by θgFp, a straight line expressed by θgFp=αp×νdp+βp (αp=−0.00163) is set up, ν dp and θgFp of the positive lens L AP are included in both of a domain which is specified by a straight line at a lower limit of the following condition (1) and a straight line at an upper limit of the following condition (1), and a domain which is specified by the following condition (2)
0.6400<βp<0.9000 (1)
3<ν dp<27 (2)
here, θ gFp is a ratio of a partial dispersion (ng−nF)/(nF−nC) of the positive lens L AP ; ν d p is Abbe number (nd−1)/(nF−nC) of the positive lens L AP ; nd is refractive index to d line; nC is refractive index to C line; nF is refractive index to F line; and ng is refractive index to g line.
2. The zoom optical system of the claim 1 ,
wherein
when in another rectangular coordinate system in which a horizontal axis is expressed by νdp and an vertical axis is expressed by θhgp, a straight line expressed by θhgp=αhgp×νdp+βhgp (here, αhgp=−0.00225) is set up, ν dp and θhgp of the positive lens L AP are included in both of a domain which is specified by a straight line at a lower limit of the following condition (3), and a straight line at an upper limit of the condition (3), and a domain which is specified by the following condition (2)
0.5700<βhgp<0.9500 (3)
3<νdp<27 (2)
here, θ hgp is a ratio of a partial dispersion (nh−ng)/(nF−nC) of the positive lens L AP ; νdp is Abbe number (nd−1)/(nF−nC) of the positive lens L AP ; nd is refractive index to d line; nC is refractive index to C line; nF is refractive index to F line; ng is refractive index to g line: and nh is refractive index to h line.
3. The zoom optical system of the claim 1 or 2 satisfying the following condition (4),
0.08 ≦θ gFp−θ gFn≦ 0.50 (4)
here, θ gFp is a ratio of a partial dispersion (ng−nF)/(nF−nC) of the positive lens L AP ; θ gFn is a ratio of a partial dispersion (ng−nF)/(nF−nC) of the negative lens L AN ; nC is refractive index to C line; nF is refractive index to F line; and ng is refractive index to g line.
4. The zoom optical system of the claim 3 satisfying the following condition (5),
0.090 ≦θ hgp−θ hgn≦ 0.60 (5)
here, θ hgp is a ratio of a partial dispersion (nh−ng)/(nF−nC) of the positive lens L AP ; θ hgn is a ratio of a partial dispersion (nh−ng)/(nF−nC) of the negative lens L AN ; nC is refractive index to C line; nF is refractive index to F line; ng is refractive index to g line; and nh is refractive index to h line.
5. The zoom optical system of the claim 1 , 2 , or 4 satisfying the following condition (6),
ν dp−ν dn≦− 30 (6)
here, ν dp is Abbe number (nd−1)/(nF−nC) of the positive lens L AP ; ν dn is Abbe number (nd−1)/(nF−nC) of the negative lens L AN ; nd is refractive index to d line; nC is refractive index to C line; and nF is refractive index to F line.
6. The zoom optical system of the claim 1 , wherein refractive index ndp to d line of the positive lens L AP satisfies the following condition (7);
1.50≦ndp≦1.85 (7).
7. The zoom optical system of the claims 1 , wherein the positive lens L AP is a lens using energy hardening type resin, which is formed directly on the negative lens L AN .
8. The zoom optical system of the claims 1 , wherein the cemented lens is constituted such that the negative lens L AN and the positive lens L AP are cemented in order from an object side.
9. The zoom optical system of the claim 1 satisfying the following condition (9), when an aspherical surface is expressed by the following formula (8), where a direction of an optical axis is z; a direction which intersects perpendicularly to the optical axis is h; a cone coefficient is k; an aspherical coefficient is represented by A 4 , A 6 , A 8 , and A 10 ; and a radius of curvature of spherical surface component on the optical axis is R,
z
=
h
2
R
[
1
+
{
1
-
(
1
+
k
)
h
2
/
R
2
}
1
/
2
]
+
A
4
h
4
+
A
6
h
6
+
A
8
h
8
+
A
10
h
10
+
…
(
8
)
here, z AC is a form of the surface at a cemented side in the positive lens L AP ; z AR is a form of the surface at an air contact side in the positive lens L AP , all of which are forms according to the condition (8); h is expressed by h=0.7 fw when the focal length of the whole zoom optical system at the wide angle end is set to fw; tp is a thickness on the optical axis of the positive lens L AP ; and z(0)=0 always.
10. The zoom optical system of the claim 1 satisfying the following conditions ( 11 )˜( 13 ),
when an aspherical surface is expressed by the following formula (8) where a direction of an optical axis is z; a direction which intersects perpendicularly to the optical axis is h; a cone coefficient is k; an aspherical coefficient is represented by A 4 , A 6 , A 8 , and A 10 ; and a radius of curvature of spherical surface component on the optical axis is R,
z
=
h
2
R
[
1
+
{
1
-
(
1
+
k
)
h
2
/
R
2
}
1
/
2
]
+
A
4
h
4
+
A
6
h
6
+
A
8
h
8
+
A
10
h
10
+
…
(
8
)
here, k AF is k value concerning a surface at the most object side in the lens group A, k AR is k value concerning a surface at the most image side in the lens group A, all of which are k values in the condition (8), z AF is k value concerning a surface at the most object side in the lens group A, and k AR is k value concerning a surface at the most image side in the lens group A, and h is expressed by h=0.7 fw, when the focal length of the whole zoom optical system at the wide angle end is set to fw.
11. The zoom optical system of the claim 1 wherein a cemented surface of the cemented lens is an aspherical surface.
12. The zoom optical system of the claim 11 wherein the aspherical surface of the cemented surface of the cemented lens has stronger convergence than that of spherical surface as it is departed from an optical axis.
13. The zoom optical system of the claim 11 or 12 wherein the difference of refraction index in d line of the positive lens L AP and the negative lens L AN is 0.2 or less.
14. The zoom optical system of the claim 1 wherein the lens group A moves firstly toward an image side, and then it moves forward direction or backward direction along the optical axis when magnification from a wide angle end to a telephoto end.
15. The zoom optical system of the claim 1 wherein the lens group B is constituted with two lens components, or a single lens component and a cemented lens component, or three lenses.
16. The zoom optical system of the claim 1 wherein a negative lens group C and a positive lens group D in which a mutual distance is variable are arranged at the image side of the lens group B.
17. Zoom optical system of the claim 16 where the lens group C consists of a negative lens only, and the lens group D consists of a positive lens only.
18. The zoom optical system of the claim 1 wherein a positive lens group C and a lens group D consisting of a meniscus lens having a convex surface directed toward the image side in which a mutual distance is variable are arranged at the image side of the lens group B.
19. The zoom optical system of the claim 18 wherein the lens group C consists of a positive lens only.
20. An imaging apparatus provided with the zoom optical system according to the claim 1 , and an image processing unit having an electronic imaging element arranged near an image forming position of the zoom optical system, wherein an image formed through the zoom optical system is photographed by the electronic imaging element, and an image data photographed by the electronic imaging element is processed electrically, and the image data can be outputted as an image data such that a shape of the image data was changed, and the following condition (19) is satisfied when focusing is carried out at nearly infinite object point,
0.7 <y 07 /( fw ·tan ω 07w )<0.94 (19)
here, y 07 is expressed by y 07 =0.7y 10 when a distance to the most distant point from a center (maximum image height) within an effective imaging surface of the electronic imaging element (within the surface in which photographing can be performed) is set to y 10 ; ω 07w is an angle to the optical axis of the direction of an object point corresponding to an image point connected to the position of y 07 from the center on the imaging surface at a wide angle end; and fw is a focal length of the whole zoom optical system at the wide angle end.Cited by (0)
No later patents cite this yet.
References (0)
No backward citations on record.